Vascular plants affect properties and decomposition of moss-dominated peat, particularly at elevated temperatures
<p>Peatlands, storing significant amounts of carbon, are extremely vulnerable to climate change. The effects of climate change are projected to lead to a vegetation shift from <i>Sphagnum</i> mosses to sedges and shrubs. Impacts on the present moss-dominated peat remain largely unk...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-10-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/17/4797/2020/bg-17-4797-2020.pdf |
| Summary: | <p>Peatlands, storing significant amounts of carbon, are
extremely vulnerable to climate change. The effects of climate change are
projected to lead to a vegetation shift from <i>Sphagnum</i> mosses to sedges and shrubs.
Impacts on the present moss-dominated peat remain largely unknown. In this
study, we used a multiproxy approach to investigate the influence of
contrasting vascular plant types (sedges, shrubs) on peat chemistry and
decomposition. Peat cores of 20 cm depth and plant material (<i>Sphagnum</i> spp., <i>Calluna vulgaris</i> and <i>Eriophorum vaginatum</i>) from two
ombrotrophic peatlands in the Italian Alps with a mean annual temperature
difference of 1.4 <span class="inline-formula"><sup>∘</sup></span>C were analyzed. Peat cores were taken under
adjacent shrub and sedge plants growing at the same height above the water
table. We used carbon, nitrogen and their stable isotopes to assess general
patterns in the degree of decomposition across sampling locations and
depths. In addition, analytical pyrolysis was applied to disentangle effects
of vascular plants (sedge, shrub) on chemical properties and decomposition
of the moss-dominated peat.</p>
<p>Pyrolysis data confirmed that <i>Sphagnum</i> moss dominated the present peat
irrespective of depth. Nevertheless, vascular plants contributed to peat
properties as revealed by, e.g., pyrolysis products of lignin. The degree of
peat decomposition increased with depth as shown by, e.g., decreasing amounts
of the pyrolysis product of sphagnum acid and increasing <span class="inline-formula"><i>δ</i><sup>13</sup>C</span>
with depth. Multiple parameters also revealed a higher degree of
decomposition of <i>Sphagnum</i>-dominated peat collected under sedges than under shrubs,
particularly at the high temperature site. Surprisingly, temperature effects
on peat decomposition were less pronounced than those of sedges. Our results
imply that vascular plants affect the decomposition of the existing peat
formed by <i>Sphagnum</i>, particularly at elevated temperature. These results suggest that
changes in plant functional types may have a stronger impact on the soil
carbon feedback in a warmer world than hitherto assumed.</p> |
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| ISSN: | 1726-4170 1726-4189 |